--- /usr/lib/python3.3/cgi.py	2014-03-22 15:19:36.000000000 +0100
+++ /tmp/cgi.py	2014-06-10 12:18:31.029412177 +0200
@@ -548,7 +548,7 @@
             if maxlen and clen > maxlen:
                 raise ValueError('Maximum content length exceeded')
         self.length = clen
-        if self.limit is None and clen:
+        if self.limit is None and clen >= 0:
             self.limit = clen
 
         self.list = self.file = None